A conventional elbow connector has been widely disclosed and is well known as a medium connector that facilitates the connection between a cable and a high-voltage device such as a switch, a transformer, or the like in a padmount.
Such an elbow connector is connected to or disconnected from, for example, a bushing insert, attached to a bushing well of a switch so as to be connected to the switch via a cable.
An exemplary elbow connector is disclosed in Patent Document 1 (Korean Unexamined Patent Publication No. 10-2008-0024646, published on Mar. 19, 2008).
That is, the elbow connector of Patent Document 1 includes an insulation housing that has a multi-layer structure, in which an internal insulating layer formed of a rubber-like insulating material is internally and externally surrounded by a semi-conductive protection layer formed of a rubber-like elastomer, such that a cable receiving part in a vertical direction and a bushing connection part and a voltage defection part in a horizontal direction are formed in a horizontally symmetric manner.
The elbow connector also includes a conductor that is assembled in a state of protruding in the central portion of the bushing connection part and the voltage detection part while forcedly engaging wires of a high voltage cable through an internal space of the cable receiving part and to which a stud bolt screwed onto a bushing insert attached to a switch is assembled.
Further, the elbow connector includes an insulation plug in which a fastening nut and a test point, which are screwed onto a rear end of the stud bolt, are insert-molded onto front and rear ends of an insulating material so as to be coupled to the voltage detection part, and an insulation cap that covers the test point exposed to a rear end of the insulation plug.
The cable includes an adapter assembled onto an insulation cladding in order to prevent shaking in the cable receiving part and to facilitate sealed assembly.
The elbow connector of Patent Document 1 has a function of detecting a voltage using the test point of the insulation plug so as to check an activated state of a distribution line or detecting a phase of power source side and load side and checking an open phase state thereof.
In order to eliminate the drawbacks of Patent Document 1 wherein the protruded length of the voltage detection part side is increased, a technique is disclosed in Patent Document 2 (Korean Patent No. 10-1066526, registered on Sep. 15, 2011) in which an asymmetric structure is formed such that a length of the voltage detection part is made smaller than a bushing connection part, and a manipulation ring of the insulation cap is made into a folded type, thereby reducing the protruded length of the voltage detection part to the max.
Although Patent Documents 1 and 2 have a function of checking an activated state of a distribution line or detecting a phase of power source side and load side and checking an open phase state thereof, configurations of Patent Documents have a problem in that, when a cable is intended to be grounded as necessary, the configurations should have a switch having a separate ground switch therein. Further, in the case of a conventional elbow connector having no grounding function. It is first disconnected from a switch and then a separate grounding elbow connector is connected to the switch so as to check a voltage and ground itself, leading to troublesome, complex work and providing inconvenience and limitations in use.
In other words, a conventional elbow connector has drawbacks in that, since it has no grounding function, upon replacement of a cable in a switch or line working, a switch having a separate grounding switch therein should be employed, or a separate grounding connector should be connected thereto so as to check a voltage and ground itself, leading to complex replacement of a cable, increased size of the switch, and limited range in use.